1. Field of the Invention
The present invention relates to an OLED technical field, and more particularly to an OLED device, in which the molecular conjugated planes of carrier transport layers are parallel to each other and stand upright on electrodes.
2. Description of the Prior Art
An OLED (Organic Light-Emitting Diode) has become a new generation of a flat panel display technology. It does not need a backlight, and adopts a very thin coating of organic material and a glass substrate. When supplying a current to the OLED, the organic material will emit light.
Please refer to FIG. 1, a conventional OLED device 9 includes an anode 91, a hole transport layer 93, a luminance layer 94, an electron transport layer 95 and a cathode 97. Electrons are injected into the electron transport layer 95 from the cathode 97, and positive holes are injected into the hole transport layer 93 from the anode 91. The injected electrons and holes recombine in the luminance layer 94 to emit light. For improving the performance of the OLED device 9, usually a hole injection layer 92 is inserted between the anode 91 and the hole transport layer 93 to be convenient for the holes to be injected into the hole transport layer 93, and an electron injection layer 96 is inserted between the electron transport layer 95 and the cathode 97 for greatly reducing the energy barrier between the cathode 97 and the electron transport layer 95 and reducing the drive pressure.
Presently, the carrier transport layers of the OLED device are amorphous films formed by an evaporation source being heated to evaporate and then being condensed on the electrode. This kind of the amorphous films transports the carriers by the carrier transition between the molecules, so the molecular structure in the films is an important factor restricting the carriers.
Please refer to FIGS. 2 to 4, FIG. 2 is a molecular structure of the film material of the carrier transport layer 93(95) of the prior OLED device, FIG. 3 is a geometric shape schematic view of the molecular structure of FIG. 2, and FIG. 4 is a microstructure schematic view of the carrier transport layer 93(95) of the prior OLED device. The molecular structure of the film material of the carrier transport layer 93(95) of the prior OLED device has great conjugated bonds, is a rigid planar structure, and horizontally stacks on the electrode 91(97) to form a film having a certain thickness. This film is constructed by multiple molecule layers 90. Specifically, in the carrier transport layer 93(95) of the prior OLED device, a long axis 93 (as shown by FIG. 3) of the molecular structure in each molecule layer 90 is parallel to the electrode 91(97). Though each molecule layer 90 has a high conductivity due to the conjugated bonds, when transporting the carriers, because the transport direction A of the carriers is perpendicular to the long axis 98 of the molecular structure, the carriers must overcome the molecular attraction between the molecule layers 90 to complete the transition. Accordingly, the carrier-transporting ability of the carrier transport layer 93(95) of the prior OLED device mainly relies on the carrier transition between the molecule layers 90, but this kind of the carrier transport layer 93(95) is difficult to improve the carrier mobility.
Hence, it is necessary to provide a new OLED device to overcome above defect.